So it would seem from Sale's POV, he's giving up $11.5M next season to get a guaranteed contract in '25 worth an additional $2M and $10M (possibly $15M) in deferred money paid upfront. From Atlanta's POV, with the $17M from Boston, they're essentially getting him for free in '24 and $1M off the $22M in 2025, plus there's no buyout on the '26 option that he's not going to get anyway. It seems like their plan for acquiring Sale from the beginning was to pay him in 2025 for the services they hope he renders in 2024... and if he does that, whatever they get from him in 2025 is gravy. I'm not sure I'd feel very confident about a pitcher who seems desperate to get the 2025 option converted to guaranteed money.
EDIT: I misread and seemed to be well short on the amount Sale is giving up in 2024.